Testing 5; Traction Circuit Problems - Toro Greensmaster TriFlex 3320/3420 Service Manual

Traction Circuit Problems

Problem
Neutral is difficult to find or unit oper-
ates in one direction only.
Traction response is sluggish.
No traction exists in either direction.
Wheel motor will not turn.
Wheel motor will not hold load in
neutral.
NOTE: The piston pump used on Greensmaster Tri-
Flex machines is equipped with relief valves for both the
forward and reverse direction. Due to engine output, it
is unlikely that traction pressure will reach relief valve
settings. If, however, a piston pump relief valve is leak-
ing or otherwise faulty, traction performance would be
affected.
Greensmaster 3320/3420
Possible Cause
External traction control linkage is misadjusted, disconnected, bind-
ing or damaged.
Piston (traction) pump is worn or damaged (see Piston (Traction)
Pump Flow Test in the Testing section of this chapter).
Hydraulic oil is very cold.
Parking brake is applied or incorrectly adjusted.
Piston pump by--pass valve is open or defective.
Charge pressure is low (see Charge Relief Valve Pressure Test in
the Testing section of this chapter).
Relief valve(s) in piston (traction) pump are leaking or damaged.
Wheel motor(s) is worn or damaged (see Wheel Motor Efficiency
Test in the Testing section of this chapter).
Piston (traction) pump is worn or damaged (see Piston (Traction)
Pump Flow Test in the Testing section of this chapter).
Parking brake is applied or incorrectly adjusted.
Oil level in reservoir is low (other hydraulic systems also affected).
Piston pump by--pass valve is open.
Charge pressure is low (see Charge Relief Valve Pressure Test in
the Testing section of this chapter).
Relief valve(s) in piston (traction) pump are leaking or damaged.
Wheel motor(s) is worn or damaged (see Wheel Motor Efficiency
Test in the Testing section of this chapter).
Piston pump is worn or damaged (see Piston (Traction) Pump Flow
Test in the Testing section of this chapter).
Brakes are binding.
Key on wheel motor shaft is sheared or missing.
Wheel motor is damaged.
Make up fluid from charge pump is not available.
Piston pump relief valves are damaged.
Page 5 - - 25 Hydraulic System